1. Field of the Invention
The present invention generally relates to methods and devices for sorting particles in a fluid such that a single particle may be isolated and analyzed.
2. Description of the Related Art
Microfluidic devices have a unique and distinct advantage for manipulating and analyzing a single particle, such as a biological cell, microorganism or a biomolecule like a protein, polynucleotide, polysaccharide, lipid, and the like.
Several microfluidic techniques have been developed to manipulate, e.g., transport and immobilize, individual cells in an array, such as (1) dielectrophoretic trapping, which confines cells in a potential well created by electrodes but involves complicated chip fabrication processes; (2) holographic optical trapping limited by the induced photodamage on the cell after an extended period of time; (3) microwell trapping characterized by a random and slow cell loading step given its reliance on gravitational forces. See e.g. Gascoyne et al. (2002) J. Electrophoresis 23:1973-1983; Fuchs et al. (2006) Lab on a Chip 6: 121-126; Voldman et al. (2002) Anal. Chem. 74:3984-3990; Neuman et al. (1999) Biophysical J. 77:2856-2863; Rettig & Folch (2005) Anal. Chem. 77:5628-5634; and Wheeler et al. (2003) Anal. Chem. 75:3581-3586; Tan & Takeuchi (2007) PNAS 104(4):1146-1151, and Shah & Lange (2007) “A microfluidic system to capture single cells” available on the World Wide Web 2 (www2) at mic.dtu.dk/research/MIFTS/publications/3 week/Jun2007_CellCapture.pdf. Unfortunately, these prior art methods and devices for transporting and immobilizing a single particle for further analysis or processing often suffer from problems of poor efficiency of capture, clogging of the microfluidic channel, and low throughput of single particles.
Therefore, a need exists for methods and devices which have high efficiency and high throughput without clogging.